1. Field of the Invention
The present invention relates to a computer bus rack having an increased density of card slots. More specifically, the present invention relates to increasing the density of card slots in a CPCI system.
2. Description of Related Art
Compact Peripheral Component Interconnect (xe2x80x9cCPCIxe2x80x9d) is a high performance industrial bus based on the standard PCI electrical specification in rugged 3U or 6U Eurocard packaging. CPCI is intended for application in telecommunications, computer telephony, real-time machine control, industrial automation, real-time data acquisition, instrumentation, military systems or any other application requiring high speed computing, modular and robust packaging design, and long term manufacturer support. Because of its extremely high speed and bandwidth, the CPCI bus is particularly well suited for many high-speed data communication applications such as servers, routers, converters, and switches.
Compared to standard desktop PCI, CPCI supports twice as many PCI slots (8 versus 4) and offers a packaging scheme that is much better suited for use in industrial applications. Conventional CPCI cards are designed for front loading and removal from a card cage. The cards are firmly held in position by their connector, card guides on both sides, and a faceplate that solidly screws into the card cage. Cards are mounted vertically allowing for natural or forced air convection for cooling. Also, the pin-and-socket connector of the CPCI card is significantly more reliable and has better shock and vibration characteristics than the card edge connector of the standard PCI cards.
Conventional CPCI defines a backplane environment that is limited to eight slots. More specifically, the bus segment of the conventional CPCI system is limited to eight slots, which includes a system slot and peripheral slots. The system slot provides the clocking, arbitration, configuration, and interrupt processing for up to seven peripheral slots. However, many applications require larger systems so that it would be advantageous to provide a higher density of slots for a given form factor.
The present invention relates to a computer bus rack including a circuit board that is adapted to have an increased density of add-on card slots for a given form factor. Important advantages and benefits are realized by providing a higher density of card slots for a computer bus rack such as a CPCI system. If the system of the present invention allows for a greater number of xe2x80x9cintelligentxe2x80x9d cards (i.e., cards having a microprocessor or a digital signal processor) to be inserted in the additional slots, then the system""s processing power is effectively increased, and more clients can be served. If more xe2x80x9cslavexe2x80x9d cards (i.e., cards having an I/O processor such as Ethernet, and serial and/or parallel ports or a storage control processor such as Small Computer System Interface (SCSI), and fiberchannel) are inserted in the additional slots, then the system""s I/O or storage capabilities are effectively increased, and more clients can be served. Either scheme also allows for a myriad of application enhancements such as multiple communication links, disk mirroring, flexible peer-to-peer transactions, and parallel and/or distributed processing. Note that the present invention is able to realize the above benefits without any increase in the physical size of the system.
In an embodiment of the invention, a computer bus rack includes at least one circuit board having a front side and a back side, and the rack comprising a first plurality of slots coupled to the front side, and a second plurality of slots coupled to the back side. The first and second plurality of slots are arranged such that corresponding ones of the first and second slots are in substantial alignment, respectively. Also, a plurality of connectors having respective connector-pins are extended in a direction substantially perpendicular to and away from the circuit board and having a column and row arrangement within the connectors. The connectors are affixed to the circuit board in alignment with the first and second plurality of slots, and each one of the plurality of connectors has connector-pins that are physically distinct from connector-pins of connectors of the other slots. Note that in the present embodiment, the slots on the front side and the back side are adapted to mate with add-on cards so as to increase the amount of add-on slots for a given form factor.
In another embodiment of the invention, a computer chassis for housing a computer bus rack is provided. The computer chassis comprises a front and rear card cage, where each of the card cages include vertical side panels parallel to each other and spaced apart, top and bottom support members parallel with respect to each other and connected to the side panels at the top and bottom of the panels, respectively, and in a direction substantially perpendicular to the panels. Also included are pairs of card guides coupled to the top and bottom support members and extended perpendicular to the support members, wherein each of the pairs of card guides includes a first card guide coupled to the top support member and a second card guide coupled to the bottom support member. Further, a board slot is located at substantially a middle portion of the chassis and in between the first and second card cages. The present embodiment is able to accommodate the computer bus rack of the present invention at the middle of the chassis instead of the back of the chassis as in the prior art. This allows for insertion of add-on cards through the front or back of the chassis. The card guides are also provided and arranged within the chassis such that the add-on cards are able to mate properly with slots of the computer bus rack.
In another embodiment of the invention, a table for holding a circuit board having connectors with connector-pins is provided. The table comprises a top surface, a bottom surface beneath the top surface, and a plurality of side surfaces disposed between the top and bottom surfaces, wherein the top surface has grooves in a direction parallel to one side surface of the table. The grooves provide a clearance for the connectors of the circuit board such that the connectors fit within the grooves, and the remaining portions of the top surface provide support to the circuit board. The present embodiment allows for press fitting of connectors to a circuit board having a single midplane implementation. For example, if there is only one midplane and the connectors are to be press-fitted on both sides of the midplane, a table as described in the present embodiment is required so that there is clearance for the already press-fitted connectors when connectors are being press-fit on another side of the midplane.
A more complete understanding of the present invention will be afforded to those skilled in the art, as well as a realization of additional advantages and objects thereof, by a consideration of the following detailed description of the preferred embodiment. Reference will be made to the appended sheets of drawings, which will first be described briefly.